Soundproofing - what's really possible?

[Ben]

Hi,

my wife and I are thinking of buying a 1970s semi-detached house. We are a bit concerned about noise from the neighbouring house; as far as I can tell they're not noisy neighbours, but we did find that standing in the front room, we could hear them talking next door.

I'm wondering to what extent it's really possible to soundproof a semi- detached house. I don't want to eliminate all noise completely, but I'd rather not be able to hear the TV or conversations from next door. I'm not so worried about occasional noises like slamming doors.

We're willing to spend quite a lot of money, if necessary, but would prefer not to lose too much space (although we recognise we'll probably have to lose a few inches of space in the rooms that are being soundproofed - about 20ft of wall on each of two floors, I guess).

I've read lots of discussion from the archives of this newsgroup and have looked at some sites that offer soundproofing services, but I've not been able to draw any real conclusions about what's really possible. Will solutions that involve putting up an additional wall of about 60mm thickness (which seems to be the standard thing offered by the sites I've looked at) really make a big difference? I found one really useful posting that said that a loud TV might be 90db, a normal party wall might cut out 45db and sound below 20db is inaudible, meaning you'd need to cut an additional 25db. Does that sound right? Is cutting 25db feasible?

Thanks in advance to anyone who can offer any advice. Also, if anyone has had experience of soundproofing a semi, I'd love to hear how you got on, and how successful you'd say it was.

Ben

[<me9]

We were in a 60s semi. We moved to a detached. The only way to soundproof.

60s/early70s were probably the worst for soundproofing, single skin block walls. Standards have improved since, but an extra 25dB is a lot to achieve without building a solid brick separate wall isolated from the existing structure.

[sm_jamieson]

My house is halls-together 1930s. 9" brick walls. You can hear loud talking next door in the hall, but of course, the living rooms are fine. Also, no worries about disturbing the neighbours. In the bathroom (on a party wall), I went paranoid, and built an inch- thick glass-fibre-reinforced concrete wall isolated from the party wall (!). A friend of a friend build a complete new skin to create a cavity wall in a semi. Moved the joists out of the party wall and everything. I expect it was very affective. A lot of rigid mass is required to block the sound effectively. Simon.

[sm_jamieson]

"effective" of course - it didn't bring the neighours out in a burst of pomposity. Simon.

[George (dicegeorge)]

Re: Soundproofing - what's really possible?

having removed some plaster i have discovered that, though the dividing wall between the neighbours is double brick, where the joists for the upstairs floor go through it there are gaps with no bricks in them so sound has been going up through my ceiling, through the gaps, and down through their ceiling, i dont know what they are having for breakfast!

so i suggest before adding sound insulation check for gaps- perhaps moving a stethoscope or glass tumbler and ear around your wall may find any such weak spots!

[g]

[dom]

Building control regulations/guidance on sound insulation:

of pragmatic advice.

But I'd go with one of the other replies here - buy a different house.

[sm_jamieson]

When I was lifting the upstairs floor and fiddling around I left the floor up for a couple of days. Shortly I realised I did in fact know what the neighbour was having for breakfast, all meals in fact (smell, not sight). Filled around joists in party wall with expanding foam and problem solved. I did have visions of her coming back to her fried egg and finding a pan full of yellow foam ! Simon.

[R D S]

> Lots of pragmatic advice.

You can get it as quiet as you like with the current neighbours, but unless you can guarrantee that they won't move out and the worlds worst chavscum move in (like in our case*) then you can never be sure of peace.

*I suppose it could be worse, they haven't kicked or stabbed me to death yet.

[John]

We used to hear next door most when they were downstairs and we were upstairs - and vice versa. I guess the space between the ceiling and floor was the main problem.

[John]

Why on earth did you do all that to soundproof a *bathroom* wall? Surely you're not going to spend much time in there, are you? Or are your farts super-duper scarily loud? :o)

John

[John]

Go for a 1930's semi. Anything from 60's onwards is a nightmare for sound pollution.

John

[Andrew Gabriel]

There's a w "In a victorian house, you couldn't even hear a baby being born next door, whereas in a modern house, you can hear it being conceived."

[sm_jamieson]

No but my neighbour's (in similar previous house) were ! And as for his elephantine nose-blowing ! And when you are in the bath you are very close to the wall, which magnifies the problem :0) Simon.

[Doctor Drivel]

Use spray in foam in the gaps. Where joists penetrate walls there is always an acoustic bridge.

What does that mean?

[Doctor Drivel]

That was referring to "Pugging", filling the floors with sand or ash.

[Pufter]

I solved this problem in my 60's semi by building a timbe

frame/plasterboard lined walls in front of the party wall in each room I have lost about 3/4 inches, but was well worth it. No plastered/decorated, etc, you would never know. It can work as long a you pay attention to detail, eg. ensure you don't directly connect an part of the timer frame to the floor/ceiling joists (I used rubbe packing, plus removed the floorboards/ceiling to minimise touch-point

- re noise transmission). Also, it should not touch the party wall a any point. Filled the void with dense glassfibre based insulation slab bought on the internet (do not go to Wickes/B&Q - not dense enough) then lined the whole lot with a blanket of floor felt (comes in blue o a big roll from B&Q). Over that, I nailed 2 sheets of 12.5m plasterboard, plus used PVA to bond the second layer to the first. Th felt isolates the plasterboard from the timber, is extra soun proofing, & the glue bonds the boards to maximise mass. Now I know fo a fact my neighbours have one of them big home cinema set-ups, plus large LCD TV mounted direct on the party wall in their kids bedroom but I don't hear a thing

-- Pufter

[Doctor Drivel]

3/4"? The double plaster board would come to that at least, then the studs to hold it.

Did this touch the party wall?

Fermacell pre-finished boards have a make up like MDF. Lots of mass. Mass stops sound. These alone can stop sound quite well, dense rockwool would help (not glass)

what you did and preventing ceiling and floor boards touching the party wall is essential. The rubber around the frame helps reducing flanking sounds.

Fermacell is so rigid doubling it up, using small bolts, would be a strong enough partition in itself, and no frame needed. And no plasterer needed.

[sm_jamieson]

Could you let us know the size of the gap and studs ? If used 2x3 studs + 1" gap + 1" plasterboard, that would be 5 inches. Simon.

[Dave Plowman (News)]

The joists run side to side? I'd say that is a serious hazard in event of a fire.

[sm_jamieson]

Quite usual in my experience. Downstairs usually front to back, upstairs side to side. But joists should be offset on both sides so there is always some brick between. Simon.